.\" This file is part of GDBM.  -*- nroff -*-
.\" Copyright (C) 2013-2022 Free Software Foundation, Inc.
.\"
.\" GDBM is free software; you can redistribute it and/or modify
.\" it under the terms of the GNU General Public License as published by
.\" the Free Software Foundation; either version 3, or (at your option)
.\" any later version.
.\"
.\" GDBM is distributed in the hope that it will be useful,
.\" but WITHOUT ANY WARRANTY; without even the implied warranty of
.\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
.\" GNU General Public License for more details.
.\"
.\" You should have received a copy of the GNU General Public License
.\" along with GDBM. If not, see <http://www.gnu.org/licenses/>. */
.TH GDBMTOOL 1 "August 1, 2021" "GDBM" "GDBM User Reference"
.SH NAME
gdbmtool \- examine and modify a GDBM database
.SH SYNOPSIS
\fBgdbmtool\fR\
 [\fB\-lmNnqrs\fR]\
 [\fB\-b\fR \fISIZE\fR]\
 [\fB\-c\fR \fISIZE\fR]\
 [\fB\-f\fR \fIFILE\fR]\
 [\fB\-\-block\-size\fR=\fISIZE\fR]\
 [\fB\-\-cache\-size\fR=\fISIZE\fR]\
 [\fB\-\-file\fR \fIFILE\fR]\
 [\fB\-\-newdb\fR]\
 [\fB\-\-no\-lock\fR]\
 [\fB\-\-no\-mmap\fR]\
 [\fB\-\-norc\fR]\
 [\fB\-\-quiet\fR]\
 [\fB\-\-read\-only\fR]\
 [\fB\-\-synchronize\fR]\
 [\fIDBFILE\fR] [\fICOMMAND\fR [; \fICOMMAND\fR...]]
.sp
\fBgdbmtool\fR\
 [\fB\-Vh\fR]\
 [\fB\-\-help\fR]\
 [\fB\-\-usage\fR]\
 [\fB\-\-version\fR]
.SH DESCRIPTION
The
.B gdbmtool
utility allows you to view and modify an existing GDBM database or to
create a new one.
.PP
The \fIDBFILE\fR argument supplies the name of the database to open.
If not supplied, the default name
.B junk.gdbm
is used instead.
If the named database does not exist, it will be created.  An existing
database can be cleared (i.e. all records removed from it) using the
\fB\-\-newdb\fR option (see below).
.PP
Unless the \fB\-N\fR (\fB\-\-norc\fR) option is given, after startup
.B gdbmtool
looks for file named
.B .gdbmtoolrc
first in the current working directory, and, if not found there, in
the home directory of the user who started the program.  If found,
this file is read and interpreted as a list of
.B gdbmtool
commands.
.PP
Then
.B gdbmtool
starts a loop, in which it reads
commands from the standard input, executes them and prints the results on the
standard output.  If the standard input is attached to a console,
the program runs in interactive mode.
.PP
The program terminates when the
.B quit
command is given, or end-of-file is detected on its standard input.
.PP
Commands can also be specified in the command line, after the \fIDBFILE\fR
argument. In this case, they will be interpreted without attempting to
read more commands from the standard input.
.PP
If several commands are supplied, they must be separated by
semicolons (properly escaped or quoted, in order to prevent them from
being interpreted by the shell).
.PP
A
.B gdbmtool
command consists of a command verb, optionally
followed by one or more arguments, separated by any amount of white
space.  A command verb can be entered either in full or in an
abbreviated form, as long as that abbreviation does not match any other
verb.
.PP
Any sequence of non-whitespace characters appearing after the command
verb forms an argument.  If the argument contains whitespace or
unprintable characters it must be enclosed in double quotes.  Within
double quotes the usual escape sequences are understood, as
shown in the table below:
.sp
.nf
.ta 8n 20n
.ul
	Escape	Expansion
	\\a	Audible bell character (ASCII 7)
	\\b	Backspace character (ASCII 8)
	\\f	Form-feed character (ASCII 12)
	\\n	Newline character (ASCII 10)
	\\r	Carriage return character (ASCII 13)
	\\t	Horizontal tabulation character (ASCII 9)
	\\v	Vertical tabulation character (ASCII 11)
	\\\\	Single slash
	\"	Double quote
.fi
.PP
In addition, a backslash immediately followed by the end-of-line
character effectively removes that character, allowing to split long
arguments over several input lines.
.SH OPTIONS
.TP
\fB\-b\fR, \fB\-\-block\-size\fR=\fISIZE\fR
Set block size.
.TP
\fB\-c\fR, \fB\-\-cache\-size\fR=\fISIZE\fR
Set cache size.
.TP
\fB\-f\fR, \fB\-\-file\fR=\fIFILE\fR
Read commands from \fIFILE\fR, instead of from the standard input.
.TP
\fB\-l\fR, \fB\-\-no\-lock\fR
Disable file locking.
.TP
\fB\-m\fR, \fB\-\-no\-mmap\fR
Do not use
.BR mmap (2).
.TP
\fB\-n\fR, \fB\-\-newdb\fR
Create the database, truncating it if it already exists.
.TP
\fB\-q\fR, \fB\-\-quiet\fR
Don't print initial banner.
.TP
\fB\-r\fR, \fB\-\-read\-only\fR
Open database in read-only mode.
.TP
\fB\-s\fR, \fB\-\-synchronize\fR
Synchronize to disk after each write.
.TP
\fB\-h\fR, \fB\-\-help\fR
Print a short usage summary.
.TP
\fB\-\-usage\fR
Print a list of available options.
.TP
\fB\-V\fR, \fB\-\-version\fR
Print program version
.SH SHELL COMMANDS
.TP
.BR avail 
Print the 
.BR "avail list" .
.TP
\fBbucket\fR \fINUM\fR
Print the bucket number \fINUM\fR and set is as the current one.
.TP
.BR cache
Print the bucket cache.
.TP
.B close
Close the currently open database.
.TP
.BR count
Print the number of entries in the database.
.TP
.BR current
Print the current bucket.
.TP
\fBdelete\fR \fIKEY\fR
Delete record with the given \fIKEY\fR.
.TP
.BR dir
Print hash directory.
.TP
.BR downgrade
Downgrade the database from the extended \fInumsync\fR format to the
standard format.
.TP
\fBexport\fR \fIFILE\-NAME\fR [\fBtruncate\fR] [\fBbinary\fR|\fBascii\fR]
Export the database to the flat file \fIFILE\-NAME\fR.  This is equivalent to
.BR gdbm_dump (1).

This command will not overwrite an existing file, unless the 
.B truncate
parameter is also given.  Another optional parameter determines the type of
the dump (*note Flat files::).  By default, ASCII dump will be created.
.TP
\fBfetch\fR \fIKEY\fR
Fetch and display the record with the given \fIKEY\fR.
.TP
.BR first
Fetch and display the first record in the database.  Subsequent
records can be fetched using the
.B next
command (see below).
.TP
\fBhash\fR \fIKEY\fR
Compute and display the hash value for the given \fIKEY\fR.
.TP
.BR header
Print file header.
.TP
.BR help " or " ?
Print a concise command summary, showing each command letter and
verb with its parameters and a short description of what it does.
Optional arguments are enclosed in square brackets.
.TP
.B history
Shows the command history list with line numbers.  This command is
available only if the program was compiled with GNU Readline.
.TP
\fBhistory\fR \fICOUNT\fR.
Shows \fICOUNT\fR latest commands from the command history.
.TP
\fBhistory\fR \fIN\fR \fICOUNT\fR.
Shows \fICOUNT\fR commands from the command history starting with \fIN\fRth
command.
.TP
\fBimport\fR \fIFILE\-NAME\fR [\fBreplace\fR] [\fBnometa\fR]
Import data from a flat dump file \fIFILE\-NAME\fR.
If the
.B replace
argument is given, any records with the same keys as the already
existing ones will replace them.  The
.B nometa
argument turns off restoring meta-information from the dump file.
.TP
\fBlist\fR
List the contents of the database.
.TP
\fBnext\fR [\fIKEY\fR]
Sequential access: fetch and display the next record.  If the \fIKEY\fR is
given, the record following the one with this key will be fetched.
.TP
\fBopen\fR \fIFILE\fR
Open the database file \fIFILE\fR.  If successful, any previously
open database is closed.  Otherwise, if the operation fails, the
currently opened database remains unchanged.

This command takes additional information from the variables
.BR open ,
.BR lock ,
.BR mmap ", and"
.BR sync .
See the section
.BR VARIABLES ,
for a detailed description of these.
.TP
.B quit
Close the database and quit the utility.
.TP
.BR reorganize
Reorganize the database.
.TP
\fBset\fR [\fIVAR\fR=\fIVALUE\fR...]
Without arguments, lists variables and their values.  If arguments are
specified, sets variables.   Boolean variables can be set by specifying
variable name, optionally prefixed with \fBno\fR, to set it to
\fBfalse\fR.
.TP
\fBsnapshot\fR \fIFILE\fR \fIFILE\fR
Analyzes two database snapshots and selects the most recent of them.
In case of error, prints a detailed diagnostics.  Use this command to
manually recover from a crash.  For details, please refer to the chapter
.B "Crash Tolerance"
in the
.BR "GDBM manual" .
.TP
\fBsource\fR \fIFILE\fR
Read commands from the given \fIFILE\fR.
.TP
.BR status
Print current program status.
.TP
\fBstore\fR \fIKEY\fR \fIDATA\fR
Store the \fIDATA\fR with the given \fIKEY\fR in the database.  If the
\fIKEY\fR already exists, its data will be replaced.
.TP
.B sync
Synchronize the database file with the disk storage.
.TP
.B upgrade
Upgrade the database from the standard to the extended \fInumsync\fR
format.
.TP
\fBunset\fR \fIVARIABLE\fR...
Unsets listed variables.
.TP
.BR version
Print the version of
.BR gdbm .
.SH "DATA DEFINITIONS"
The \fBdefine\fR statement provides a mechanism for defining key or
content structures.  It is similar to the \fBC\fR \fBstruct\fR
declaration:
.sp
.nf
.in +4
\fBdefine\fR \fBkey\fR|\fBcontent\fR \fB{\fR \fIdefnlist\fR \fB}\fR
.in
.fi
.PP
The \fIdefnlist\fR is a comma-separated list of member declarations.
Within \fIdefnlist\fR the newline character looses its special meaning
as the command terminator, so each declaration can appear on a
separate line and arbitrary number of comments can be inserted to
document the definition.
.PP
Each declaration has one of the following formats
.sp
.nf
.in +4
\fItype\fR \fIname\fR
\fItype\fR \fIname\fR \fB[\fIN\fB]\fR
.in
.fi
.sp
where \fItype\fR is a data type and \fIname\fR is the member name.
The second format defines the member \fIname\fR as an array of \fIN\fR
elements of \fItype\fR.
.PP
The supported types are:
.sp
.nf
.ta 8n 20n
.ul
	type	meaning
	char	single byte (signed)
	short	signed short integer
	ushort	unsigned short integer
	int	signed integer
	unsigned	unsigned integer
	uint	ditto
	long	signed long integer
	ulong	unsigned long integer
	llong	signed long long integer
	ullong	unsigned long long integer
	float	a floating point number
	double	double-precision floating point number
	string	array of characters (see the \fBNOTE\fR below)
	stringz	null-terminated string of characters
.fi
.PP
The following alignment declarations can be used within \fIdefnlist\fR:
.TP
\fBoffset\fR \fIN\fR
The next member begins at offset \fIN\fR.
.TP
\fBpad\fR \fIN\fR
Add \fIN\fR bytes of padding to the previous member.
.PP
For example:
.sp
.nf
.in +4
\fBdefine content {
        int status,
        pad 8,
        char id[3],
        stringz name
}\fR
.fi
.PP
To define data consisting of a single data member, the following
simplified construct can be used:
.sp
.nf
.in +4
\fBdefine\fR \fBkey\fR|\fBcontent\fR \fItype\fR
.fi        
.PP
where \fItype\fR is one of the types discussed above.
.PP
\fBNOTE\fR: The \fBstring\fR type can reasonably be used only if it is
the last or the only member of the data structure.  That's because it
provides no information about the number of elements in the array, so
it is interpreted to contain all bytes up to the end of the datum.
.SH VARIABLES
.TP
.BR confirm ", boolean"
Whether to ask for confirmation before certain destructive operations,
such as truncating the existing database.  Default is
.BR true .
.TP
.BR ps1 ", string"
Primary prompt string.  Its value can contain \fIconversion
specifiers\fR, consisting of the \fB%\fR character followed by another
character.  These specifiers are expanded in the resulting prompt as
follows: 
.sp
.nf
.ta 8n 20n
.ul
	Sequence	Expansion
	\fB%f\fR	name of the db file
	\fB%p\fR	program name
	\fB%P\fR	package name (\fBgdbm\fR)
	\fB%_\fR	horizontal space (\fBASCII\fR 32)
	\fB%v\fR	program version
	\fB%%\fR	\fB%\fR
.fi
.sp
The default prompt is \fB%p>%_\fR.
.TP
.BR ps2 ", string"
Secondary prompt.  See
.B ps1
for a description of its value.
This prompt is displayed before reading the second and subsequent
lines of a multi-line command.

The default value is \fB%_>%_\fR.
.TP
.BR delim1 ", string"
A string used to delimit fields of a structured datum on output
(see the section \fBDATA DEFINITIONS\fR).

Default is \fB,\fR (a comma).  This variable cannot be unset.
.TP
.BR delim2 ", string"
A string used to delimit array items when printing a structured datum.

Default is \fB,\fR (a comma).  This variable cannot be unset.
.TP
.BR pager ", string"
The name and command line of the pager program to pipe output to.
This program is used in interactive mode when the estimated number of
output lines is greater then the number of lines on your screen.

The default value is inherited from the environment variable
\fBPAGER\fR.  Unsetting this variable disables paging.
.TP
.BR quiet ", boolean"
Whether to display welcome banner at startup.  This variable should
be set in a startup script file.
.PP
The following variables control how the database is opened:
.TP
.BR cachesize ", numeric"
Sets the cache size.  By default this variable is not set.
.TP
.BR blocksize ", numeric"
Sets the block size.  Unset by default.
.TP
.BR open ", string"
Open mode.  The following values are allowed:
.RS 7
.TP
.BR newdb
Truncate the database if it exists or create a new one.  Open it in
read-write mode.
.TP
.BR wrcreat " or " rw
Open the database in read-write mode.  Create it if it does not
exist.  This is the default.
.TP
.BR reader " or " readonly
Open the database in read-only mode.  Signal an error if it does not
exist.
.RE
.TP
.BR filemode ", octal"
Sets the file mode for newly created database files. Default is 0644.
.TP
.BR lock ", boolean"
Lock the database.  This is the default.
.TP
.BR mmap ", boolean"
Use memory mapping.  This is the default.
.TP
.BR coalesce ", boolean"
When set, this option causes adjacent free blocks to be merged which
allows for more efficient memory management at the expense of a
certain increase in CPU usage.
.TP
.BR centfree ", boolean"
Enables central free block pool. This causes all free blocks of space
to be placed in the global pool, thereby speeding up the allocation of
data space.
.SH "SEE ALSO"
.BR gdbm_dump (1),
.BR gdbm_load (1),
.BR gdbm (3).
.SH "REPORTING BUGS"
Report bugs to <bug\-gdbm@gnu.org>.
.SH COPYRIGHT
Copyright \(co 2013-2021 Free Software Foundation, Inc
.br
.na
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
.br
.ad
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
.\" Local variables:
.\" eval: (add-hook 'write-file-hooks 'time-stamp)
.\" time-stamp-start: ".TH GDBM[A-Z_-]* 1 \""
.\" time-stamp-format: "%:B %:d, %:y"
.\" time-stamp-end: "\""
.\" time-stamp-line-limit: 20
.\" end:
